1. Field of the Invention
The present invention relates to an imaging apparatus equipped with an anti-shake (image shake correction/image stabilizing/shake reduction) system.
2. Description of the Related Art
In recent years, mobile electronic devices which are designed mainly for taking still/moving photographic images, such as digital cameras (still-video cameras) and digital camcorders (motion-video cameras), and other mobile electronic devices which are designed to be capable of taking such photographic images as a subsidiary function, such as mobile phones equipped with a camera and smart devices (smart phones or tablet computers, etc.) equipped with a camera, have become widespread. There has been a demand for an imaging apparatus which is incorporated in such mobile electronic devices to be equipped with a so-called anti-shake (image shake correction/image stabilizing/shake reduction) system that is designed to reduce image shake on an image plane that is caused by vibrations such as hand shake.
As an anti-shake system, a type of anti-shake system which moves (shifts) an anti-shake (image-stabilizing) optical element such as a lens group (containing at least one lens element) or an image sensor along a plane orthogonal to an optical axis and another type of anti-shake system which changes the angle of (tilts) such an anti-shake optical element relative to an optical axis are known in the art. In addition, another type of anti-shake system which drives an anti-shake optical element to spherically swing along an imaginary spherical plane having a predetermined spherical-swinging center with no directional restrictions (hereinafter referred to as the spherical swinging operation) has been proposed in Japanese Unexamined Patent Publication No. 2014-89325 (Patent Literature 1), Japanese Unexamined Patent Publication No. 2008-134329 (Patent Literature 2) and Japanese Patent No. 5,096,496 (Patent Literature 3).
In the type of anti-shake system which performs a spherical swinging operation, the spherical-swinging center of the spherical swinging operation is often set at a point on an optical axis of an optical system (or on an extension of this optical axis). However, if the support mechanism for the anti-shake system is simply arranged on this optical axis, this mechanism may interfere with an optical path of the optical system, so that it is required to take the arrangement of the support mechanism into consideration so that the support mechanism does not interfere with the optical path.
In Patent Literature 1, a correction lens group (image-stabilizing lens group) is supported by an image-shake correction unit, which provided as a movable member, and this image-shake correction unit is supported to be capable of performing a spherical swinging operation via a plurality of rollers (rolling members) installed between a portion of the image-shake correction unit which is positioned around the correction lens group and a fixed member. Accordingly, instead of arranging the support mechanism at the location of the spherical-swinging center, the spherical-swinging center is virtually set by the support mechanism that is arranged around the correction lens group. In Patent Literature 2, a correction lens group (image-stabilizing lens group) is supported to be capable of performing a spherical swinging operation via a similar structure. In the structures disclosed in Patent Literatures 1 and 2, the installation space for the support mechanism tends to be large in a direction orthogonal to an optical axis.
In Patent Literature 3, an entire camera section, which includes an optical system and an image sensor, is driven to perform a spherical swinging operation, and this camera section is supported to be capable of performing the spherical swinging operation with a protrusion as a point of support which is formed on a fixed portion. In Patent Literature 3, a substantive spherical-swinging center is set on an extension of an optical axis, and therefore it is difficult to apply the structure disclosed in Patent Literature 3 to the type of anti-shake system in which only apart of a plurality of optical elements constituting an optical system is driven to perform an anti-shake (image-stabilizing) operation. Additionally, according to the structure disclosed in Patent Literature 3, an increase in size of the anti-shake system cannot be avoided because the entire camera section is driven to perform the spherical swinging operation.
Additionally, in each of Patent Literatures 1, 2 and 3, a sensor for detecting the position of a movable member is provided on a fixed member which supports the movable member in a manner to allow the movable member to perform a spherical swinging operation. Therefore, when an adjustment is made to the position of the movable member (e.g., to the position of the spherical-swinging center), a relative positional deviation occurs between the sensor, which is provided at a fixed position, and the movable member, the position of which is to be detected by the sensor, which may exert an influence on the detection accuracy of the sensor. Even if the relative positional deviation falls within a controllable level, it is required to correct the influence caused by the positional deviation in some sort of way to detect the position of the movable member and control the driving of the movable member, which increases processing load.